Scoping queries in a search engine

ABSTRACT

Systems and methods for scoping a search. When a content index for electronic data is built, one or more scope restrictions are included in the content index. The scope restriction may be, for example, a root folder identifier, a mailbox identifier, or a URL. Because the scope restriction is included in the content index random access of the property store to determine the scope is avoided. Rather, the scope restriction is implicitly added to a search that uses the content index. By including a scope restriction in the search query, the search results identified from the content index are limited to results that match the scope restriction. Advantageously, the effect of including the scope restriction in the search is ignored if the search results are relatively small or when including the scope restriction provides little benefit.

BACKGROUND OF THE INVENTION

[0001] 1. The Field of the Invention

[0002] The present invention relates to systems and methods forsearching a data store. More particularly, the present invention relatesto systems and methods for focusing or scoping a search of the datastore by restricting the search results of a query to a particularsubset of the search results.

[0003] 2. The Prior State of the Art

[0004] One of the advantages provided by computers is the ability toelectronically store information. This information often takes the formof spreadsheets, documents, electronic messages, and databases. Storinginformation electronically is advantageous for many different reasons.Changes to the stored information can be made quickly and easily bymultiple users and the stored information can frequently beelectronically sent to another person.

[0005] Businesses, home computers, Internet sites and other computersystems all maintain stores of data. These data stores can be specificto a particular type of data or can be a general repository for data. Anexample of a data store that is specific to a type of data is a mailstore, which is primarily used to store electronic messages. In fact, amail store is a component of practically every computer system. The mailstore is highly compartmentalized, and can store a large amount of data.Usually, each user of the computer system is assigned a mailbox in themail store and the user can store electronic messages in their portionof the mail store and it is not uncommon for each user to store largenumbers of electronic messages.

[0006] Another significant advantage of storing information or dataelectronically is the ability to electronically search the information.The ability of a user to search data stores is facilitated by programsthat index those data stores. When a user submits a search query, theindex assists a user in identifying and locating data or documents thatmay interest the user. More specifically, the content index for a datastore can quickly identify those documents that match a particularsearch query. The data structures of the content index are highlycompact and are inexpensively accessed.

[0007] For example, a mail store can contain a significant amount ofdata in the form of electronic messages and for that reason, the mailstore is often indexed to facilitate a search of the mail store forspecific electronic messages. Currently, an index of the mail store willallow various messages within the mail store to be identified or locatedwhen a user specifies one or more search terms. However, many of themessages identified and located by the search are not contained in themailbox of the user performing the search. Messages that are not locatedin the user's mailbox are not useful to the user primarily because theuser does not have permission to access those messages. For that reason,the user performing the search is interested only in the messages thatare in the user's mailbox. A significant disadvantage of current searchtechniques is that extra processing time is required to identify whichmessages in the search results are located in the user's mailbox. Thisis particularly true when a server computer is indexing the content onbehalf of the user.

[0008] For example, when a user is searching the mail store, the contentindex cannot currently account for the fact that the user is usuallyonly interested in messages that are in that user's mailbox. When theuser specifies a certain search query, the content index identifies allmessages within the mail store that satisfy the search query. Thesesearch results must be reduced to those that are specific to the user'smailbox. This is accomplished by accessing the property store for eachof the messages identified from the content index to determine whichmailbox or folder contains the messages. In other words, the contentindex does not index mailbox information, which must be retrieved fromanother source such as the property store. The mailbox informationretrieved from the property store is compared against the user's mailboxinformation and only those messages that are in the user's mailbox orfolder are returned in the search results. This process can consumesignificant processing time because there may be a large number ofmessages identified by the content index and because the property storeis accessed randomly. The property store is randomly accessed becausethe messages identified by the content index are in no particular orderwith regard to the mail store. More specifically, the content index doesnot index or group the mail store according to individual mailboxes.

[0009] In other words, the ability to scope or focus a search iscurrently implemented by filtering the results obtained from the contentindex against the Uniform Resource Locator (URL) retrieved from theproperty store for each result. Only those documents whose URL matchesthe URL of the scope restriction (the user's mailbox) are ultimatelyreturned to the user. As previously indicated, the process of filteringthe results against information in the property store can take a longtime, especially because the property store is randomly accessed.

SUMMARY OF THE INVENTION

[0010] These and other problems with the prior art are overcome by thepresent invention, which is directed towards focusing and scoping asearch. A “Search Engine” or an “Internet Search Engine” is anapplication that gathers electronic data from various sources or datastores and builds a content index that can service search queries tolocate or identify electronic data that satisfies a particular searchquery.

[0011] The content index includes keys or other scope restrictions andis not limited to terms or words. By including scope restrictions in thecontent index, the search query of a user can be focused or scoped bythe content index, which eliminates the need to filter each resultagainst the property store. The extra processing time required to accessthe property store is therefore significantly reduced because accessingthe content index is much faster than accessing the property store.

[0012] When a content index is being constructed or altered, root folderidentifiers or other scope restrictions are included in the contentindex. The inclusion of the root folder identifiers in the content indexallows a user to perform a content index query for the root folderidentifier and obtain a full list of documents that are within theinitial scope of the content index. When a user performs a query withinthe initial scope, the root folder identifier is implicitly added to thesearch query criteria. This limits the search results to those documentsthat have the specified root folder identifier.

[0013] For example, a user often searches a mail store for electronicdocuments by formulating a search query having one or more terms.However, the user is only interested in search results from the user'smailbox. In accordance with the present invention, the root folderidentifier of the user's mailbox is implicitly added to the searchquery. By comparing the documents identified by both the root folderidentifier and the text or terms of the search query, the search resultsmay be limited to documents within the user's mailbox without accessingthe property store.

[0014] In some instances, the scope restriction is ignored in cases whenthe search query would otherwise return relatively few results. This canoccur, for example, when unique terms are used that occur in relativelyfew documents. The actual number of results that will effectivelyeliminate the scope restriction from the search query can be adjusted asneeded. When the scope restriction is not used, it may be necessary toaccess the property store as previously described. However, this doesnot require significant processing time because the number of documentsin the search results is small.

[0015] Additional features and advantages of the invention will be setforth in the description which follows, and in part will be obvious fromthe description, or may be learned by the practice of the invention. Thefeatures and advantages of the invention may be realized and obtained bymeans of the instruments and combinations particularly pointed out inthe appended claims. These and other features of the present inventionwill become more fully apparent from the following description andappended claims, or may be learned by the practice of the invention asset forth hereinafter.

BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to describe the manner in which the above-recited andother advantages and features of the invention can be obtained, a moreparticular description of the invention briefly described above will berendered by reference to specific embodiments thereof which areillustrated in the appended drawings. Understanding that these drawingsdepict only typical embodiments of the invention and are not thereforeto be considered to be limiting of its scope, the invention will bedescribed and explained with additional specificity and detail throughthe use of the accompanying drawings in which:

[0017]FIG. 1 illustrates an exemplary system that provides a suitableoperating environment for the present invention;

[0018]FIG. 2 is a block diagram illustrating the creation of a contentindex;

[0019]FIG. 3 illustrates the use of the content index in performing asearch of a data store;

[0020]FIG. 4 is a diagram of a content index that includes scoperestrictions; and

[0021]FIG. 5 is a flow diagram illustrating how the content index, whichincludes scope identifiers, may be used to execute a search of a datastore.

DETAILED DESCRIPTION OF THE INVENTION

[0022] Searching a data store is often hindered by the need to scope orfocus the search results. The present invention overcomes this and otherproblems of the prior art. As used herein, “scoping” refers torestricting a search query to a particular subset of results ordocuments based on a scope restriction such as a folder identifier or aURL. Scoping also refers to producing search results from a contentindex by including the scope restrictions in the content index. Scopingsearches is particularly useful in situations where the initial scoperestrictions are well defined. For instance, the user mailboxes of amail system are the initial scope restriction for user searches of themail system and in a web crawl, the initial scope restriction can be theURLs on a given site, or a set of URLs produced by following aparticular starting URL.

[0023] Scoping search results is often necessary in order to returnvalid search results to a particular user. For example, when a usersearches a mail store, the user is usually only interested in theresults from the user's mailbox. The actual search, however, identifiesall of the messages in the data store that satisfy the search. As aresult, the search must be scoped to those messages within the searchresults that are in the user's mailbox. Previously, this wasaccomplished by accessing a property store for each document in thesearch results to identify those messages that are in the user'smailbox.

[0024] By including the scope restrictions in the content index, asearch can quickly identify the relevant subset of messages withouthaving to access the property store. Typically, the scope restrictionsare within the initial scope of the content index. For example, if theinitial scope of a content index is a mail store, then an exemplaryscope restriction would be a particular mailbox within the mail store.

[0025] The present invention extends to both methods and systems forscoping searches. The embodiments of the present invention may comprisea special purpose or general purpose computer including various computerhardware, as discussed in greater detail below.

[0026] Embodiments within the scope of the present invention alsoinclude computer-readable media for carrying or havingcomputer-executable instructions or data structures stored thereon. Suchcomputer-readable media can be any available media which can be accessedby a general purpose or special purpose computer. By way of example, andnot limitation, such computer-readable media can comprise RAM, ROM,EEPROM, CD-ROM or other optical disk storage, magnetic disk storage orother magnetic storage devices, or any other medium which can be used tocarry or store desired program code means in the form ofcomputer-executable instructions or data structures and which can beaccessed by a general purpose or special purpose computer. Wheninformation is transferred or provided over a network or anothercommunications connection (either hardwired, wireless, or a combinationof hardwired or wireless) to a computer, the computer properly views theconnection as a computer-readable medium. Thus, any such a connection isproperly termed a computer-readable medium. Combinations of the aboveshould also be included within the scope of computer-readable media.Computer-executable instructions comprise, for example, instructions anddata which cause a general purpose computer, special purpose computer,or special purpose processing device to perform a certain function orgroup of functions.

[0027]FIG. 1 and the following discussion are intended to provide abrief, general description of a suitable computing environment in whichthe invention may be implemented. Although not required, the inventionwill be described in the general context of computer-executableinstructions, such as program modules, being executed by computers innetwork environments. Generally, program modules include routines,programs, objects, components, data structures, etc. that performparticular tasks or implement particular abstract data types.Computer-executable instructions, associated data structures, andprogram modules represent examples of the program code means forexecuting steps of the methods disclosed herein. The particular sequenceof such executable instructions or associated data structures representexamples of corresponding acts for implementing the functions describedin such steps.

[0028] Those skilled in the art will appreciate that the invention maybe practiced in network computing environments with many types ofcomputer system configurations, including personal computers, hand-helddevices, multi-processor systems, microprocessor-based or programmableconsumer electronics, network PCs, minicomputers, mainframe computers,and the like. The invention may also be practiced in distributedcomputing environments where tasks are performed by local and remoteprocessing devices that are linked (either by hardwired links, wirelesslinks, or by a combination of hardwired or wireless links) through acommunications network. In a distributed computing environment, programmodules may be located in both local and remote memory storage devices.

[0029] With reference to FIG. 1, an exemplary system for implementingthe invention includes a general purpose computing device in the form ofa conventional computer 20, including a processing unit 21, a systemmemory 22, and a system bus 23 that couples various system componentsincluding the system memory 22 to the processing unit 21. The system bus23 may be any of several types of bus structures including a memory busor memory controller, a peripheral bus, and a local bus using any of avariety of bus architectures. The system memory includes read onlymemory (ROM) 24 and random access memory (RAM) 25. A basic input/outputsystem (BIOS) 26, containing the basic routines that help transferinformation between elements within the computer 20, such as duringstart-up, may be stored in ROM 24.

[0030] The computer 20 may also include a magnetic hard disk drive 27for reading from and writing to a magnetic hard disk 39, a magnetic diskdrive 28 for reading from or writing to a removable magnetic disk 29,and an optical disk drive 30 for reading from or writing to removableoptical disk 31 such as a CD-ROM or other optical media. The magnetichard disk drive 27, magnetic disk drive 28, and optical disk drive 30are connected to the system bus 23 by a hard disk drive interface 32, amagnetic disk drive-interface 33, and an optical drive interface 34,respectively. The drives and their associated computer-readable mediaprovide nonvolatile storage of computer-executable instructions, datastructures, program modules and other data for the computer 20. Althoughthe exemplary environment described herein employs a magnetic hard disk39, a removable magnetic disk 29 and a removable optical disk 31, othertypes of computer readable media for storing data can be used, includingmagnetic cassettes, flash memory cards, digital video disks, Bernoullicartridges, RAMs, ROMs, and the like.

[0031] Program code means comprising one or more program modules may bestored on the hard disk 39, magnetic disk 29, optical disk 31, ROM 24 orRAM 25, including an operating system 35, one or more applicationprograms 36, other program modules 37, and program data 38. A user mayenter commands and information into the computer 20 through keyboard 40,pointing device 42, or other input devices (not shown), such as amicrophone, joy stick, game pad, satellite dish, scanner, or the like.These and other input devices are often connected to the processing unit21 through a serial port interface 46 coupled to system bus 23.Alternatively, the input devices may be connected by other interfaces,such as a parallel port, a game port or a universal serial bus (USB). Amonitor 47 or another display device is also connected to system bus 23via an interface, such as video adapter 48. In addition to the monitor,personal computers typically include other peripheral output devices(not shown), such as speakers and printers.

[0032] The computer 20 may operate in a networked environment usinglogical connections to one or more remote computers, such as remotecomputers 49 a and 49 b. Remote computers 49 a and 49 b may each beanother personal computer, a server, a router, a network PC, a peerdevice or other common network node, and typically include many or allof the elements described above relative to the computer 20, althoughonly memory storage devices 50 a and 50 b and their associatedapplication programs 36 a and 36 b have been illustrated in FIG. 1. Thelogical connections depicted in FIG. 1 include a local area network(LAN) 51 and a wide area network (WAN) 52 that are presented here by wayof example and not limitation. Such networking environments arecommonplace in office-wide or enterprise-wide computer networks,intranets and the Internet.

[0033] When used in a LAN networking environment, the computer 20 isconnected to the local network 51 through a network interface or adapter53. When used in a WAN networking environment, the computer 20 mayinclude a modem 54, a wireless link, or other means for establishingcommunications over the wide area network 52, such as the Internet. Themodem 54, which may be internal or external, is connected to the systembus 23 via the serial port interface 46. In a networked environment,program modules depicted relative to the computer 20, or portionsthereof, may be stored in the remote memory storage device. It will beappreciated that the network connections shown are exemplary and othermeans of establishing communications over wide area network 52 may beused.

[0034]FIG. 2 is a block diagram generally illustrating an environment orsystem in which the present invention may be implemented. FIG. 2 alsoillustrates the construction or alteration of a content index. The store200 is an exemplary medium for storing data and may be a computerreadable medium as described above. The store 200 can be used tospecifically store a particular type of data, such as word processingdocuments, electronic messages such as e-mails, or the like, or can beused to store many different types of data. The store 200 can also bepartitioned. For example, when the store 200 is a mail store used tostore electronic messages, the store 200 is often partitioned intomailboxes. The store 200 can also refer to multiple data stores. Forexample, the store 200 can be the Internet.

[0035] The search engine 202 is a computer program or process thatgathers electronic documents and other data from the store 200 to createa content index 210. The search engine 202 gathers data from any numberof different stores or different server computers and the like. As aresult, the content index 210 is an index or reflection of theelectronic data kept on the stores searched or crawled by the searchengine 202. One advantage of the content index 210 is that a search fordata on the store 200 is aided by the content index 210. The scope ofthe content index 210 is therefore described by the store 200. The scopeof the content index 210 is not limited, however, to a single datastore. Similarly, a single data store can be indexed by more than onecontent index 210. For discussion purposes, the store 200 is generallyreferred to as a mail store that is partitioned into multiple mailboxes.However, the store 200 can be used for other types of data.

[0036] In addition to indexing the terms or words of the documents anddata being gathered from the store 200, scope restrictions such asfolder identifiers are also placed in the content index 210 as thecontent index is being created or built. If a particular data store doesnot provide a folder identifier, then a URL that matches the initialscope is applied during the gathering process. The folder identifier isunique across all other folder identifiers and is indexed along with theother documents included in the initial scope. The scope restrictionsare sometimes considered to be non text even though the scoperestrictions may be represented in the content index alphanumerically.URLs, for example, can be treated as either text or non-text. In thecase of a mail store, the content index 210 will likely include adifferent folder identifier for each mailbox.

[0037]FIG. 3 is an illustration of the context index 210 and a propertystore 204. As illustrated, the content index 210 includes keys 212 whichare closely associated with document identifiers 214. The full textcontent index now includes non-textual data that allows the search queryto be executed more rapidly. Because searches are often performed onwords or terms, the keys 212 are typically implemented as words, termsor text. For example, the word “patent” may be a key in the contentindex 212 and this specific key is associated with the documentidentifiers 214 of those documents that contain the specified key orword. In this manner, the content index 210 identifies all of thedocuments or other data that contain the identified key or word. Thekeys 212 can also be illustrated as groups of words, phrases, Booleanexpressions, and the like.

[0038] In a typical search where the content index 210 does not includescope restrictions or other identifiers, the keys 212 are used toidentify the document identifiers 214. Even though the documents areidentified, their location within the store 200 is unknown. Thelocations or Uniform Resource Locators (URLs) of the documents in thestore 200 are stored in the document properties 215. In other words, theproperty store 214 links the document identifiers 214 to the documentproperties 215. In order to actually locate the documents identified bythe document identifiers 214, the property store 215 must be accessedand queried for the location of each document or search result. Anotheridentifier that is used to locate a document in the store 214 is thecombination of a folder identifier (FID) and a message identifier (MID).The binary structure of the FID and the MID allows a particular messagein a mail store to be found very quickly.

[0039] As previously indicated, this can be a lengthy task in certaincircumstances. For example, if a user is searching for documents withina particular folder on the store 200, then the document properties 215must be accessed for both the location of the document as well as whichfolder each document is in. Because the content index 214 only maintainsthe document identifiers 214, the property store 215 is randomlyaccessed to determine these values for each document identifier providedfrom the content index 210. In other words, the organization of thedocument identifiers 214 does not usually correspond to the organizationof the document properties 215. For this reason, the property store isaccessed randomly for the document identifiers 214 identified from thecontent index 210. If the number of document identifiers 214 is large,then the process of identifying those documents that are specific to aparticular folder can consume significant processing time. Because theproperty store is accessed randomly, the search engine may actually haveto access a disk for each search result instead of memory. Accessing adisk is very slow when compared to accessing memory.

[0040]FIG. 4 illustrates another example of the content index 210 thatcan significantly reduce the processing time required to identifyspecific documents because the content index shown in FIG. 4 includesscope restrictions. Often, the content index 210 is constructed as abalanced tree 216 that is able to minimize access times. The contentindex 210 can also be structured using other data structures thatoptimize access times. In some instances, the content index 210 iscompressed as well.

[0041] In the case of the tree 216, the nodes are often representativeof specific keys as previously described. A list of document identifiersis usually associated with each node or key. In FIG. 4, the node 222 isthe portion of the tree 216 that represents the term 223. The documentidentifier list 220 is associated with the term 223 and the node 222.Thus, when a person searches for a particular key, word, or term, thecontent index 210 can identify the documents that contain the key, word,or term by the document identifiers found in the document identifierlist 220.

[0042] As previously discussed, prior art indexes are unable to scopethe document identifiers returned by those indexes. The content index210 illustrated in FIG. 4 overcomes this limitation by including scoperestrictions such as folder identifiers “FIDs” in the content index 210.Usually, the root FID that identifies an entire mailbox is used becauseusers typically search within their own mailboxes. In this example, thedocument identifier list 219 includes document identifiers that arecontained in a particular folder. The folder identifier is included as akey and the folder identifier is indexed within the content index 210.Thus, the node 224 is the portion of the tree 216 that represents an FIDand the document identifier list 219 is associated with the FID 221 andthe node 224. The tree 216 can contain other nodes that are associatedwith other FIDs or with other scope identifiers. In this manner, aparticular FID, such as the FID 221 can be used to identify a particularsubset or search results that are in a particular folder or location.More specifically, the document identifier list 219 can be used toreduce or trim the document identifier list 220 such that the remainingdocument identifiers in the document identifier list 220 are containedin the folder associated with the FID 221.

[0043] Thus, including the FIDs in the content index 210 allows a userquery to be scoped to a particular subset of documents based on the URLor other scope restriction. Because the search is focused or scoped bythe FID, URL or other scope restriction, the costly processing action ofaccessing the property store is effectively eliminated. Including theFID in this manner is particularly useful in data stores that are highlypartitioned. Another advantage of including the scope restrictions inthe content index 210 is that the user does not have to explicitlyinclude the scope restriction in the search query. Rather, the scoperestriction is implicitly added to the search query.

[0044] For example, in a mailbox store, a user may desire to search forall documents containing a particular key or term. If the FID is notincluded in the content index, then the property store will have to beaccessed for each document identifier in the document identifier list.Because the document identifiers in the document identifier list are notin any particular order, the property store is randomly accessed. Aspreviously mentioned, this can be a computationally expensive action.

[0045] In FIG. 4, the FID 221 of the actual mailbox,http://mymailstore/mymailbox, is indexed in the content index 210.Instead of accessing the property store for each document identifier,the document identifiers in the document identifier list 220 arecompared against the document identifiers in the document identifierlist 219. The result of this comparison, which identifies a subset ofdocuments in mymailbox that satisfy the search query, is returned in thesearch results. In other words, the document identifiers that appear inboth document identifier lists are returned to the user. Thus, theuser's search query is scoped or focused to the user's own mailbox inthis example.

[0046] The comparison of the document identifier list 219 with thedocument identifier list 220 is not always performed in order tooptimize the search query. For example, if the document identifier list220, which represent the documents that contain the term 223, is small,then no comparison is made with the document identifier list 219.Instead, the property store will be accessed for those documents becauseit is computationally less expensive.

[0047]FIG. 5 is a flow diagram that illustrates how including scoperestrictions such as the FID in the content index can focus or scope asearch. In step 500, the search query is received. The search queryusually contains one or more terms or combination of terms. In step 508,an FID or other identifier is added to the search query. Usually, theroot FID that identifies an entire mailbox is used because userstypically search within their own mailboxes. The search query thuscontains keys or words specified by the user plus the FID, root folderidentifier, or other identifier. In step 510, the search is performedusing both the keys and the root folder identifier to determine oridentify the document identifiers stored in the content index thatsatisfy the search.

[0048] In step 512, the document identifiers for the root folderidentifier are examined against the document identifiers for the keys orwords and a determination is made as to whether the document identifiersassociated with the root folder identifier can reduce the overall numberof document identifiers to be returned to the user. This often dependson the number of document identifiers associated with both the keys andthe root folder identifier as well as the relative sizes of the sets ofdocument identifiers.

[0049] If the list of document identifiers for the keys is small incomparison to the list of document identifiers associated with the rootfolder identifier, then no comparison is made between the lists and theresults of the search query are returned to the user in step 506. Forexample, if the relative sizes of the sets of document identifiers is 8to 1 or less, then no comparison is made between the lists and theresults of the search query are returned in step 506. If the list ofdocument identifiers for the keys is large in comparison to the list ofdocument identifiers associated with the root folder identifier, thenthe lists are compared and the resulting set of document identifiers isreduced in step 514 and the reduced set of results for the search queryare returned to the user in step 506. Exemplary comparisons between thedocument identifier lists 219 and 220 include determining which documentidentifiers exist in both lists, subtracting the list 219 from the list220, and the like.

[0050] The implicit use of the root folder identifier included in thecontent index is judiciously used such that the processing time requiredto identify the relevant document identifiers is improved. Using FIG. 4as an example, a comparison between the document identifier lists maynot be performed when processing the search query if the documentidentifier list 219 is larger than the document identifier list 220.More generally no comparison is performed between the documentidentifier lists 219 and 220 when it is computationally efficient toonly process the document identifier list 220 as previously described.It is more efficient, in some cases, to perform a slow operation such asrandomly accessing the property store a small number of times ratherthan perform a fast operation a large number of times. When thiscondition is met, the effect of including the scope restriction or otheridentifier in the search is removed.

[0051] The present invention may be embodied in other specific formswithout departing from its spirit or essential characteristics. Thedescribed embodiments are to be considered in all respects only asillustrative and not restrictive. The scope of the invention is,therefore, indicated by the appended claims rather than by the foregoingdescription. All changes which come within the meaning and range ofequivalency of the claims are to be embraced within their scope.

What is claimed and desired to be secured by United States LettersPatent is:
 1. In a system including a data store, wherein the data storeis indexed by a content index using terms, a method for scoping a searchof the data store, wherein the search includes one or more terms, themethod comprising: an act of including an identifier in the contentindex, wherein the identifier is implicitly included in the search; anact of identifying a first list of document identifiers with the one ormore terms from the content index; an act of identifying a second listof document identifiers with the identifier from the content index; andan act of comparing the second list of document identifiers with thefirst list of document identifiers to identify a subset of documentidentifiers that satisfy the search.
 2. A method as defined in claim 1,wherein the act of including an identifier in the content index furthercomprises an act of building the content index.
 3. A method as definedin claim 1, further comprising an act of returning the subset ofdocument identifiers.
 4. A method as defined in claim 1, wherein the actof comparing the second list of document identifiers with the first listof document identifiers further comprises an act of restricting thesearch based on the identifier.
 5. A method as defined in claim 1,wherein the identifier is a folder identifier.
 6. A method as defined inclaim 5, wherein the folder identifier is unique across the contentindex.
 7. A method as defined in claim 1, wherein the identifier is aUniform Resource Locator.
 8. A method as defined in claim 1, wherein theact of comparing the second list of document identifiers with the firstlist of document identifiers further comprises an act of intersectingthe second list of document identifiers with the first list of documentidentifiers to identify the subset of document identifiers.
 9. A methodas defined in claim 1, further comprising an act of refraining fromcomparing the second list of document identifiers with the first list ofdocument identifiers when the second list of document identifiers cannotreduce the first list of document identifiers.
 10. A method as definedin claim 1, further comprising an act of refraining from comparing thesecond list of document identifiers with the first list of documentidentifiers when processing only the first list of document identifiersis more efficient.
 11. In a system including one or more data stores,wherein a search engine gathers and indexes data from the one or moredata stores in a content index, a method for focusing a search of thedata, the search including one or more terms, the method comprising: anact of including one or more scope restrictions in the content indexwhen the search engine indexes the data, wherein the one or more scoperestrictions are non-text; an act of adding a scope restriction to thesearch, the scope restriction included in the one or more scoperestrictions; an act of identifying a first list of document identifiersfrom the content index using the one or more terms of the search; an actof identifying a second list of document identifiers from the contentindex using the scope restriction; and an act of focusing the first listof document identifiers by using the second list of document identifiersto generate a subset list of document identifiers from the first list ofdocument identifiers.
 12. A method as defined in claim 11, furthercomprising an act of returning the subset list of document identifiersto a user.
 13. A method as defined in claim 11, wherein the act ofincluding one or more scope restrictions in the content index furthercomprises an act of building the content index.
 14. A method as definedin claim 11, wherein the act of focusing the first list of documentidentifiers further comprises an act of scoping the search based on thescope restriction.
 15. A method as defined in claim 11, wherein thescope restriction is a folder identifier.
 16. A method as defined inclaim 15, wherein the folder identifier is unique across the contentindex.
 17. A method as defined in claim 11, wherein the scoperestriction is a Uniform Resource Locator.
 18. A method as defined inclaim 11, wherein the act of focusing the first list of documentidentifiers further comprises an act of intersecting the second list ofdocument identifiers with the first list of document identifiers.
 19. Amethod as defined in claim 11, wherein the act of focusing the firstlist of document identifiers further comprises an act of identifyingmatching document identifiers from the first list of documentidentifiers and the second list of document identifiers, wherein thematching document identifiers are included in the subset list ofdocument identifiers.
 20. A method as defined in claim 11, furthercomprising an act of refraining from focusing the first list of documentidentifiers using the second list of document identifiers when thesecond list of document identifiers cannot reduce the first list ofdocument identifiers.
 21. A method as defined in claim 11, furthercomprising an act of refraining from focusing the first list of documentidentifiers when processing only the first list of document identifiersis more efficient.
 22. A computer readable medium having computerexecutable instructions for performing the acts recited in claim
 11. 23.In a system including a mail store partitioned into one or moremailboxes, wherein a search engine has indexed the mail store in acontent index, a method for scoping a search of the mail store, thesearch including one or more terms, the method comprising steps for: thesearch engine including one or more identifiers in the content index,wherein the one or more identifiers identify the one or more mailboxes;including a root folder identifier in the search, the root folderidentifier included in the one or more identifiers; identifying a firstlist of document identifiers from the content index using the one ormore terms, wherein the first list of document identifiers correspond tomessages in the one or more mailboxes; identifying a second list ofdocument identifiers from the content index using the root folderidentifier, wherein the second list of document identifiers correspondto messages in a mailbox identified by the root folder identifier; andgenerating a subset list of document identifiers by removing documentidentifiers from the first list of document identifiers that do notmatch document identifiers in the second list of document identifiers.24. A method as defined in claim 23, wherein the step for generating asubset list of document identifiers further comprises a step forcomparing the first list of document identifiers with the second list ofdocument identifiers.
 25. A method as defined in claim 23, wherein thestep for generating a subset list of document identifiers furthercomprises a step of intersecting the second list of document identifierswith the first list of document identifiers.
 26. A method as defined inclaim 23, wherein the step for generating a subset list of documentidentifiers further comprises a step for identifying matching documentidentifiers from the first list of document identifiers and the secondlist of document identifiers, wherein the matching document identifiersare included in the subset list of document identifiers.
 27. A method asdefined in claim 23, further comprising a step for refraining fromgenerating a subset list of document identifiers when it is efficient toonly process the first list of document identifiers.
 28. A method asdefined in claim 27, further comprising a step for accessing a propertystore for the first list of document identifiers.
 29. A method asdefined in claim 23, further comprising a step for returning the subsetlist of document identifiers.
 30. A method as defined in claim 23,wherein the folder identifier is a URL.
 31. A method as defined in claim23, the folder identifier is a set of URLs.
 32. A computer readablemedium having computer executable instructions for performing the stepsrecited in claim 23.